This invention pertains generally to the testing of containers such as soft drink beverage bottles, and more particular to apparatus for testing such containers for the ability to withstand internal pressure and for the absence of leaks.
Heretofore, several different approaches have been employed or suggested for testing bottles for beverages such as soft drinks and other similar containers. The purpose of such testing is to determine whether the bottles are sufficiently strong to resist internal pressure and are free of defects which may cause leaks.
These approaches have included the application of mechanical pressure to the exterior of a bottle and the application of pneumatic pressure to the interior of a bottle. Each of these approaches has certain limitations and disadvantages. It is difficult to apply a mechanical pressure uniformly over the entire exterior of a bottle, and it is also difficult to detect defects in the crown of the bottle which may cause leaks. With an internally applied pneumatic pressure, when a bottle fails, it does so with explosive force, hurling pieces of broken glass which can injure nearby personnel and become lodged in the machinery.
U.S. Pat. Nos. 3,826,126 and Re. 31,385 disclose a better approach in which a bottle is first filled with low pressure water to expel air and other gases from the bottle, following which high pressure water is introduced into the bottle and the ability of the bottle to withstand the pressure without leakage or other failure is observed. This approach has the advantage of accurately simulating the pressure to which the bottle is subjected when it is filled with product and capped, and it also avoids the danger of exploding glass in the event that the bottle should fail. While this approach represents a definite improvement over the other prior art approaches for testing bottles, this approach still has certain limitations and disadvantages.